Study the distribution of microbial cross-reactive antigens in two categories of human tumors, i.e., leukemia and melanoma, by using antisera to Mycobacterium bovis and to other microbial components, and employing the submitted clinical protocols, study patients with benign disease, and normal donors as well as cancer patients in remission, relapse, progression or regression phases of their disease for evaluation of the clinical efficacy of monitoring the level of circulating cross-reactive antigens.